Adding to Mentat7’s technique:
After modeling all of your objects, place them on a small canvas size that is proportional to what you’ll ultimately work on. Place markers for each as you go. When they are all placed, clear the canvas and change the document size to your actual working size.
At this point, you’ll probably want to increase the marker radius in the Preferences palette. Go through the document and use every marker that you’d placed to re-draw the object. It will automatically be scaled to fit the larger canvas size, but without any of the nightmares of trying to position them on a large canvas. One click, and it’s in place!
For my own personal technique, I then usually zoom out so that a large part of the document is visible, and start doing general painting. As I start needing greater levels of detail, I then zoom in to actual size to focus on those areas. Since it’s just detail work at this point, it no longer usually matters that I can’t see the whole canvas.
Hope that helps!